About Serial Numbers

I don't just assign serial numbers to my products. I create a strategic numbering system. Here's how and why.

When you're building a physical product, and the product has at least some complexity, the serial numbers are an absolute must-have. Basically, anything that has an electric plug or a battery and is smarter than a desk lamp should be marked with a serial number.

The reason why we use serial numbers is simple: to track individual products to their origin (sales location, manufacturing batch, assembly line, etc.) This is needed mostly when you encounter issues with a product, and when it happens, serial numbers are essential for the investigation.

I’ve manufactured millions of units over the years, and I want to share my practical experience with you.

These are the main principles to consider when designing your serial number format.

1. Plan ahead and be consistent. It is wise to define the serial number format for your company and keep using it across multiple products for many years. This helps you keep the same procedures and software.

2. Do not use serial numbers on simple/cheap products. If the product is cheap enough so that it does not make sense to handle each return or defect case individually, use lot numbers instead of serial numbers. The difference between a lot number and a serial number is that serial numbers are assigned to individual units (all serial numbers are unique within the lot), and the lot number is the same on all units in the lot. Lot numbers are also useful to mark critical and high-cost components for better traceability.

3. Make serial numbers human-readable. Make it simple so humans can decode the serial number instantly. It simplifies both manual processing of data and automation (e.g., report generation). Do not use serial number formats that would require referring to extra records to identify which batch or product it was assigned to.

4. Keep the length short. The longer the serial number is, the more space it takes on the device (the main downside), and also, it is harder to work with. Unless you make more than a million units in every batch, and you release a new batch more often than every two weeks, 12 characters for the serial number is enough.

5. Do not put everything into the serial number. Within the serial number, keep only essential information. Essential information may include: product id, date of manufacture, assembly plant, sequential number within the lot. Everything that is not tied to significant changes in the manufacturing process, such as product variants (color, size, etc.), must not be included in the serial number format. If you want to keep track of such information, just match it to serial numbers elsewhere (in a separate spreadsheet, for example), but do not stuff it into the serial number itself.